Crankcase heaters: Purpose;
- Prevents off cycle _______ of refrigerant by warming the oil in the crankcase
- Prevents liquid _______ of refrigerant oil (flooded starts)
- prevents off cycle migration
2. prevents liquid dilution
Crankcase Heaters: Types;
- Electrical (75watt)
- Internal: insertion in a ___
- External: Wrap _____ - Coil _______
- Oil ________
- Electrical 75watt, Internal is insertion in a well and external is wrap around
- coil discharge
- oil separator
Crankcase Heater: Purpose;
- Minimizes the amount of ____ circulated through the system
- excessive oil circulation causes reduced system ______ by reducing heat transfer within the evap coil
- Especially important if the oil is not ______ with the refrigerant such as R-717 or R22 in low temp applications
- oil
- capacity
- miscible
Crankcase Heaters: Installation;
- _______ line of the system
- Return line back to ______ (with shut off valve)
- separator should be
- discharge line of the system
- return line back to crankcase
- separator should be insulated
Liquid Line Heat Exchanger: Purpose;
- Increase suction line ______ and increase liquid line ________
- Make sure they have a bit of superheat to protect the _________
- May help provide minimum _______ requirement
- Tube within a tube: vapour in suction line is ______ than liquid in liquid line
- increase suction line superheat and increase liquid line sub-cooling
- compressor
- superheat
- colder
Evaporator Pressure Regulator: (EPR)
Also known as;
- Pressure reducer _____
- Two ________ ______
- ______ pressure valve
- pressure reducer valve
- two temperature valve
- constant pressure valve
Evaporator Pressure Regulator:
- Location: At the ______ of the evaporator
- Valve operation: maintain pressure which means it opens on _____ of _____
- When inlet valve pressure is higher than spring it will ______ refrigerant to go through the valve
- Open force is _____ and closing force is the _____
- outlet
- rise of inlet
- allow
- suction, spring
Evaporator Pressure Regulator: Purpose;
- To prevent evaporator from going below a predetermined _____ or ________
- Types: (2) _____ operated and _____ operated
pressure or temperature
temp operated and press operated
Evaporator Pressure Regulator: Applications;
- Any application where an abnormally ____ temp could create a problem
- On a system operating two or more condition spaces at _______ temps
- On ______ systems one setting used for operating cycle and other setting used during ______ mode
- Multiple Evap/Temp systems EPR is installed at the _____ of the warmest coil
- low
- different
- ammonia, defrost mode
- outlet
Evaporator Pressure Regulator: Applications;
- *Check valve must be located at the _____ of the ______ coil
- Required if TD between warmest and coldest coils exceed __F
- Controlled evaporators must not exceed ___% of grand total load
- outlet of the coldest coil
- 5F
- 40%
EPR Considerations;
- At 40% EPR load, system may require capacity control using a _______ bypass valve to compressor suction, along with a de-superheating _______ valve
- A ____ tank may also be required to prevent _____ cycling
- discharge bypass valve, along with a de superheating expansion valve
- surge tank, to prevent short cycling
Solenoid Valve: Installations;
- When brazing heat rapidly and direct flame away from valve _____ to protect it from ________
- Must be _______
- Usually in ______ line could be found in _____ line for pump down or two temp applications
- Most valves use _______ to seat the valve, mount valve _______
- away from valve body to prevent overheating
- anchored
- discharge line sometimes in suction line for pump down or two temp applications
- Gravity, mount valve upright
Check Valves: Purpose;
- To ______ fluid flow
- Allow refrigerant to flow in one _______
- control
2. one direction only
Check Valve: Types;
- _____ gate
- ball
- magnetic
- swing gate
Check valve: Installation;
- When brazing heat rapidly and direct flame away from the valve _____
- Protect from ________
- must be installed with the arrow pointing in the direction of ________ flow
- away from the valve body
- overheating
- refrigerant flow
Muffler: Purpose;
- To ______ gas pulsation which helps reduce _______ transmitted to refrigerant lines
- Used in _________ compressors
- reduce gas pulsation to help reduce vibrations
2. reciprocating
Muffler: Installation;
- Mounted ________ or ________
- horz install must ensure bulge is on ___ to prevent oil trapping
- when brazing heat rapidly and direct flame away from ______
- Must be ________
- protect from _________
- Installed with arrow point in direction of ref _____
- installed _______ from compressor discharge
- horizontally or vertically
- top
- body
- anchored
- overheating
- flow
- downstream
Valves are installed at various locations in the refrigeration system to:
- insulate equipment for ______
- _____ portions of the system when refrigerant is not required in a certain area
- provide manual _____-connection from one component of system to another
- servicing
- isolate
- cross connections
Valves Classified by design: Globe valve;
- Used for ____ refrigerants
- cast body able to withstand ____ pressures
- Flow is essentially straight through from _____ to ______
- most ______ valve in use
- A _______ pressure drop than any other valve making them _________ on suction line or low pressure liquid line where pressure drop affects efficiency
- all
- high
- inlet to outlet
- common
- higher, unsuitable
Valves classified by design: Angle valve;
- Used for ___ refrigerants
- Cast body able to withstand ____ pressures
- flow through valve is at ___ degrees relative to _____ and ______
- they have lower resistance (pressure drop) than globe valves making them more suitable for use on ______ lines and low _____ liquid lines
- all
- high
- 90 degrees relative to inlet and outlet
- lower resistance pressure drop to flow then globe valves making them more suitable suction lines and low pressure liquid lines
Valves classified by design: Gate valve;
- Used in refrigeration systems with _____, ______, and glycols
- They are not used with ________ primary refrigerants as they are not manufactured for this
- gate valves are usually used up to ___mm pipe diameter over which they become physically too large and difficult to install
- water, brine, and glycol
- vaporizing primary refrigerants
- 75mm diameter
Valves classified by design: Butterfly valve;
- Have a very low ______ drop and are economical and easy to install in pipe diameters _____mm and above
- Require ______ connections
- while suitable for primary and secondary ref, some problems exist with them holding _______ when using _______ refrigerants
- Problem is the behaviour of the seating material when exposed to a mixture of ____ and _____. Hence these valves are best suited to water, brines, or glycols.
- very low pressure drop and easy to install in pipe diameters 100mm and above
- flanged
- holding pressure when used with primary ref
- ref and oil
Valves classified by design: Ball Valve;
- May be used with _______ refrigerants
- May also be used with ______ refrigerants but are more expensive than gate valves or butterfly valves
- they have the lowest _______ drop of any valve (when selected full port size in the wide open position)
- They are best suited to ____ pressure pumped liquid lines
- primary
- secondary
- lowest pressure drop
- low pressure pumped
Valves classified by design: Diaphragm valve;
- used for ____ refrigerants
- flow through the valve is ___ degrees parallel to the ______
- ______ resistance to flow (pressure drop)
- cast body able to withstand ____ pressure
- Hermetic seal between _______, diaphragm, and _______
- all
- 90 degrees parallel to inlet
- lower
- high
- bonnet, diaphragm, and body
Valves classified by design: Access Valve;
- Used to gain access to _____ systems
- They are equipped with a _______ valve
- Service lines ______ the schrader valve if equipped with a depressor
- small
- schrader
- depress
Access control valves are used to remove a _______ core while pulling a vacuum on a system
schrader
Valves classified by design: Line Piercing Valve;
- Used on small systems that do not have ______ valves
- May be installed on _________ systems
- Bolt on style tend to ____ as O ring deteriorates over time and exposure to system ___
- Brazed on ______ valve (on a vapour line)
- service valves
- pressurized
- leak, oil
- saddle valves
Split AC service valves:
- made of ____ and used for ____ temperature and pressure applications
- These valves are used with _________ refrigerants
- brass, high
2. halocarbon
Types of connection to piping: Screwed;
- Used for ____ pressures
- a usually confined to under ___mm due to difficulty in making screwed joints
- all pressures
2. under 50mm
Types of connection to piping: Flanged;
- Available from ___mm pipe diameter and up
- Usually used on pipe diameters ___mm and larger
- Whenever removal from the line is contemplated for _________ purposes
- 12mm
- 50mm and larger
- maintenance purposes
Types of connection to piping: Welded in line;
- Lightweight and easy to install compared to larger _____ and ______ valves
- The valves are becoming less expensive in pipe diameters ____mm and over
- The main disadvantage is the valve must be ____ out of the line if removal is necessary
- They should be installed in a position where _________ may be easily performed
- globe and angle valves
- 100mm and over
- cut out
- maintenance
Types of connection to piping: Brazed;
- Used where _______ and _________ is a factor in application
- Sil-foss is a ______ brazed filler
- temperature and pressure
2. common brazed filler
Types of connection to Piping: Soldered;
- Used on copper piping where ____ temperatures and pressure is not a factor
- Not used on ________ refrigerant lines
- Used for ____ lines
- high
- primary
- drain
Types of connection to piping: Flared;
- Used with ____ walled tubing up to ___mm pipe diameters
- Used with standard wall tubing up to ___” OD
- light walled up to 50mm
2. 7/8” OD
Types of enclosures: Seal cap;
- The valve packing and stem is enclosed with a _____ cap to prevent _______
- Usually used with _______ since leaks cannot be detected by _____ and the refrigerant is relatively expensive
- screwed cap, prevent leakage
2. halocarbons, can not be detected by smell
Types of Enclosures: Exposed;
- The valve packing and ____ is exposed
- _______ can occur from the packing to atmosphere
- stem
2. leakage
Valve Stem Packing:
- Provides a ____ between the system and surrounding environment
- ________ and non-_________ packing
- seal
2. replaceable and non-replaceable packing
Valve Stem Packing:
Material must be compatible with _________ and _____ used
refrigerants and oils used